Effect of extrusion processing and hydrocolloids on the stability of added vitamin B12 and physico-functional properties of the fortified puffed extrudates

Abstract

An alarming rate of increase in the prevalence of vitamin B12 deficiency has generated the demand for fortified foods therewith. This work focused on the development of vitamin B12 fortified rice extrudates wherein the effect of extrusion variables viz. die temperature (oC), screw speed (rpm) and feed rate (kg/h) on the stability of vitamin B12 and physico-functional properties were evaluated. The stability of vitamin B12 was greatly affected by die temperature and unaffected by screw speed and feed rate. The product with best physico-functional properties as obtained from experimental design (168 °C/229 rpm/4.6 kg/h) gave 54% retention of vitamin B12, while the product with best retention of 77% vitamin B12 (140 °C/150 rpm/4 kg/h) gave extrudates with low expansion ratio, WAI, WSI and high bulk density, hardness, breaking strength index and fracturability. To achieve the desirable combination of high retention of vitamin B12 and best physico-functional properties, hydrocolloids such as guar gum, xanthan gum or carboxymethyl cellulose were added at 5 and 10 g/kg of rice flour. Although all the hydrocolloids improved the physico-functional properties without affecting vitamin B12 stability, carboxymethyl cellulose at 5 g/Kg is recommended for such fortified snacks.